Blowing device for rock drills



0d. 24, 1939. E B, LEAR' 2,177,391

BLOWING DEVICE FOR ROCK DRILLS Filed Nov. 5., 1938 2 sheets-Sheet 1 4 II Sg] k I f5 /J Vial .1.. 5g |55@ 4f 6| I a 4 JLM l ze A5 -20 l 3 I e 3Zf/ 27 t 19 J 5f I i fa., 50 f 7n I 47 Y 65 5/ f4 INVENTOR ,45- TqE-.5A/e.

Q I M ATTORNEY Patented Oct. 24, 1939 UNITED STATES 4PATENT OFFICEBLOWING DEVICE FORVROCK DRILLS Application November 5, 193s, serial No.239,067

2 claims. (o1. 121-10) This invention relates to rock drills and moreparticularly to an arrangement for delivering a continuous stream ofcompressed air through the ydrill steel for blowing detritus out of thedrilled hole whenever the usual intermittent supply of air is insufcientto keep the hole clean.

An object of the invention is the provision of a blowing device that issimple in construction, easy to manipulate and dependable in operation.

Another object is to adapt the blowing apparatus to be incorporated in aconventional rock drill without requiring extensive alteration of thelatter for this purpose.

Other objects and features will appear more clearly from the followingdescription taken in connection with the accompanying drawings andappended claims.

In the accompanying drawings Fig. 1 is a longitudinal section of afragmentary portion of a rock drill embodying the invention, showing theblower valve arranged in the drilling position; and

Fig. 2 is a similar view on a larger scale showing the valve arranged inthe blowing position.

In the illustrative embodiment of the invention `2li the drill comprisesa cylinder 4 providing a piston chamber 5 in which a hammer piston 6reciprocates, the machine being provided with conventional rotationmechanism for imparting stepby-step rotary movement to the piston. Suchmechanism may comprise a rifle nut 'I screwed to the piston, a rifle bar8 having helical splines slidably engaging the rifle nut, a head 9 onthe rifle bar, a series o-f pawls I0 carried by the head, and astationary ratchet ring I I surrounding the head and pawls. The ratchetring is supported by the cylinder 4 and by a back head I2 rigidlysecured to the cylinder.

I The cylinder has a counterbore I3 which'receives a valve chestcomprising a valve case I4 and valve cap I5. The valve cap abuts againstthe ratchet ring I I to prevent axial movement of the latter. The valvecap has an annular projection or sleeve I6 forming a bearing for therifle bar 8 and surrounded by the valve case I4. The interior of thevalve case is recessed to provide a plurality of spaced grooves orchambers which forconvenience may be designated as follows: `rear endgroove I'I which is in constant cornmunication with the rear end of thepiston chamber by means of ports I8; live air groove I9, continuouslysupplied with pressure fluid; front end groove 20 communicating by'meansof passageway ZI with the front end of the piston chamber; exhaustgroove 22, vented toatmosphere; l and an annular chamber 23.. n

lpiston chamber. vmits live pressure fluid from the supply groove Anannular distributing valve 25 is mounted for limited axial reciprocationon the valve cap extension I6. The valve and valve cap extension yhavecomplementary engaging surfaces of different diameters providing ashoulder 26 on the 5 inside of the valve which is adapted to be suppliedwith live pressure uid constantly tending to move the valve forward.Near its rear end, the valve 25 has a flange 21 projecting into thechamber 23 of the valve chest and dividing said chamber into twoseparate sections. The section in front of the flange Z'I is ventedthrough port 28. The section in back of the ange connects with a port 29adapted to be connected (by means hereinafter described) to a cylinderport 3B. The 15 piston chamber 5 has a main exhaust port 3| adapted tobe connected to atmosphere when the machine is conditioned for thedrilling operation. The port 30 is disposed to the rear end of the mainexhaust 3I. 20

The back head I2 is provided with a manipulative throttle valve 33adapted, when in the open position, to supply compressed air to anannular groove 34. The air passes from groove 34 through the spaceseparating the rie bar head 9 from the 25 ratchet ring II, to an annulargroove 35 in the valve cap I5. Passages 36 and 31 deliver live air fromthe annular groove 35 to the internal shoulder 26 on the valve and thelive air groove I9, respectively. 30

'The operation of the mechanism described up to this point is asfollows: Assume that the parts are as shown in Fig. 1 with the piston 6and the distributing valve 25 in their forward positions. Pressure fluidpasses from the live air groove I9, 35 over the valve groove 39 to thegroove 20 and passageway 2| leading to the forward end of the pistonchamber. rlhe piston moves rearward since the rear end of the piston isvented through the main exhaust port 3l. In its rearward travel, 40

`the piston covers the main exhaust and, after closing port 30,compresses the air trapped in the rear end of the piston chamber. Thepressure of the trapped air acts against the area at the front end ofthe valve 25 (in groove I'I) and, when this 45 pressure reaches theproper value, it overcomes the opposing pressure on the internalshoulder 26 to trip the valve rearwardly.

When the distributing valve 25 is in its rearward position, asillustrated in Fig. 2, the valve groove 39 connects the front end groove20 with the exhaust groove 22 to vent the front end of the At the sametime the valve ad- I9 to the rear end groove I'I from whence the air 55passes through the openings`I8 to the rear end of the piston chamber,thus driving the piston forwardly. At the start of the forward travel ofthe piston, the air in front of the piston head is vented through themain exhaust port 3 I. As the piston closes the main exhaust port, theair in front of the piston head is exhausted through the passageway 2|.

During its forward travel, piston 6 uncovers port 30 thereby allowingpressure fluid from the rear end of the piston chamber to enter thevalve chest port 29 and chamber 23, where it acts on the rear face ofthe valve flange 21. The combined area of the rear face of iiange 21 andthe shoulder 26 is considerably greater than'the area.

of the front end of the valve and consequently the valve trips forwardto the Fig. 1 position, thus completing a cycle of operation.

If desired, an exhaust port 4I may belconnected to the rear end of theannular chamber 23 in the valve chest inorder to vent the uid in thispart of the chamber before the opposite compression stroke 'of the valvetakes place. Port 4I, however, should be restricted in diameter in orderto permit pressure to build up in chamber 23 when the piston uncoversthe port 30 during its forward movement.

The drilling operation is substantially the same as in priorconstructions. The present invention is directed to the arrangement forpermitting live air to pass in ra continuous stream through the drillsteel while the piston is held stationary. As seen in Fig. 1, the frontend of the piston has a central bore 43 registering with the bore 44 inthe drill steel 45. According to the present invention, the piston isheld in the position shown in Fig. 1 while the main exhaust port SI isclosed and pressure fluid is delivered to the rear end of the pistonchamber 5 from whence it passes between the splines on the riiie bar 8and ride nut 'I to the piston bore 43 and drill steel Vbore 44 to blowthe detritus from the bottom of the hole being drilled.

For this purpose, the cylinder 4 is provided with a housing 41 in whichis secured a valve chest 48. The valve chest has an exhaust port 49leading to atmosphere. A blower valve 5U, mounted for turning movementin valve chest 48, has a recess 5I `adapted to connect the cylinderexhaust port 3| with the valve chest exhaust port 49, when the blowervalve is adjusted to the Fig. 1 position. Another recess 52 is adaptedto connect port 3|] with a passage 53 leading to the port 29 in thevalve chest I4 to effect forward tripping of the valve in the mannerhereinbefore described.

When the blower valve is adjusted to the blowing position, as shown inFig. 2, the main cylinder exhaust port 3I is cut off from communicationwith the atmospheric port 49. Passage 53 is disconnected from the port3l) and is connected to atmosphere by a port 54 in the blower Valve 50,for the purpose of relieving any pressure that might build up at therear face of the distributing valve flange 2l. Assuming the distributingvalve is in the kposition shown in Fig. 2, compressed air is delivered`by the supply groove I9, through groove I'I and ports I8 to the rearend of the piston chamber 5, from whence the compressed air passesthrough the piston 6 and drill steel 45 to remove the detritus from thebottom of the drilled hole. l The valve is held in the Fig. 2 positionby the pressure acting against the front end of the valve whichpredominates over the pressure against internal shoulder 26 and isunopposed by any pressure against the rear face of flange Z'I.

When the drill is used as a sinker and if the blower valve is closedbefore the throttle valve 22 is opened, both the piston and thedistributing valve will be in the lower or forward position as shown inFig. 1. In order to insure movement of the distributing valve to theFig. 2 position under these conditions, a restricted port 56 may beprovided between the live air groove I9 and the rear end groove I1 inthe valve chest I 4. The purpose of the restricted port 56 is to permita gradual leakage of pressure fluid into the rear end of the pistonchamber until the pressure therein increases to an amount sufficient totrip the valve to 4the Fig. r2 position by acting against the front endthereof. The restricted port 56, while useful as aprecautionary measureis not indispensable, since there may be sumcient leakage between thegrooves I9 and ILV-due to the slight clearance at the periphery of thedistributing valve.

What is claimed is:

.1. A rockvdrill comprising a ycylinder providing a piston chamber, 4apiston reciprocable therein, said cylinder having 'a main exhaust portseparating the front and rear ends of .the piston chamber and adapted tobe overrun by the piston in both directions, `a source of live pressurefluid, means 'including 'anautomatic distributing Valve for distributingpressureuid from said source to fthe respective lends of the pistonchamber, said distributing valve having a rst area in constantcommunication with the rear end of the piston chamber and intermittentlyexposed to live pressure uid and fluid compressed by the rearwardmovement of the piston for moving the distributing valve in onedirection, a second area opposed to said rst-area and of larger extentand intermittently exposed to fluid pressure under control of the pistonfor moving the distributing valve in the oppcsitedirection, said pistonbeing adapted to deliver impacts against a drill steel and having a boreadapted to deliver pressure fluid to the drill steel for blowingpurposes, a blower valve housing 'carried by the cylinder, a blowervalve adjustably mounted therein, said blower valve and housing havingcomplementary ports and passages adapted in one position Vof the blowervalve to connect the main cylinder exhaust port to atmosphere and thesecond area on said distributing valve to a port at the rear portion ofthe piston chamber to condition the drill for drilling operation, saidcomplementary ports and passages being adapted in another position ofadjustment of the blower valve to close the main cylinder exhaust portfrom atmosphere and disconnect said second area on the distributingValve from .itsassociated piston chamber port and connect said secondarea to atmosphere to hold the distributing Valvey and piston in aposition for dtelivering air throughsaid piston bore to the drill s eel.

2. A rock drill comprising a cylinder providing .a piston chamber, apiston reciprocable therein, said cylinder having a. main exhaust portseparating the front and rear ends of the piston chamber kand :adaptedto be Yoverrun by the piston in both directions, a source of live'pressure fluid, means `including an automatic distributing valve fordistributing pressure fluid from said source to the respective ends ofthe piston chamber, said distributing valve having a first area inconstant communication with the rear end of the piston chamber andintermittently exposed to live pressure fluid and fluid .compressed bythe rearward movement of the piston for moving the distributing Valverearwardly, a second area opposed to said iirst area and of largerextent and intermittently exposed to fluid pressure under control of thepiston for moving the distributing valve forwardly, a third area of lessextent than and opposed to said first area and continuously exposed tolive pressure fluid under constant pressure for assisting in the forwardmovement of the distributingvalve and holding it in its forward positionwhen pressure on said second area becomes relatively low, said pistonbeing adapted to deliver impacts against a drill steel and having a boreadapted to supply pressure fluid to the drill steel for blowingpurposes, a blower valve housing carried by the cylinder, a blower valveadjustably mounted therein, said blower valve and housing havingcomplementary ports and passages adapted in one position of the blowervalve to connect the main cylinder exhaust port to atmosphere and thesecond area on said distributing valve to a port at the rear portion ofthe piston chomber to condition the drill for drilling operation, saidcomplementary ports and passages being adapted to another position ofadjustment of the blower valve to close the main cylinder exhaust portfrom atmosphere and disconnect said second area on the distributingvalve from its associated piston chamber port and connect said secondarea to atmosphere to hold the distributing valve and piston in aposition for delivering air through said piston bore to the drill steel,and a restricted passageway constantly delivering a minute stream oflive pressure fluid from said source to the rear end of the pistonchamber to gradually build up pressure in the latter to trip the valveto its rear position, in opposition to pressure against said third area.

EARL B. LEAR.

